How-to enable "hairpin_addressing" in Terraform Enterprise FDO Docker

Expected Outcome

Add a host mapping to the Terraform Enterprise container to resolve the TFE hostname to the private IP address of the instance.

Prerequisites

•  Terraform Enterprise Flexible Deployment Options Docker

Use Case

Migrating from a Replicated installation to Flexible Deployment Options and want to enable the equivalent of hairpin_addressing.

Procedure

• Edit the Compose YAML file  and add the extra_hosts block with the hostname:IP mapping, ex:
  

  name: terraform-enterprise
  services:
    tfe:
    ...
    ...
      extra_hosts:
        - "tfe.example.net:162.242.195.82"

• Stop/Start TerraformEnterprise using Systemd(if set up), otherwise manually with:
  

  # Commands must be run from the folder containing the Compose YAML file
  docker compose down
  docker compose up -d

• Verify the changes have been successfully applied(replace container name appropriately if needed):

  # Inspect your tfe docker container
  docker inspect terraform-enterprise -f '{{.HostConfig.ExtraHosts}}' 
  [tfe.example.net:162.242.195.82]
  
  # Check hosts file inside of the container
  docker exec -it terraform-enterprise bash -c 'egrep $TFE_HOSTNAME /etc/hosts'
  162.242.195.82 tfe.example.net

NOTE: To enable hairpin_addressing for Terraform runs set TFE_RUN_PIPELINE_DOCKER_EXTRA_HOSTS as described in the link below.

Additional Information

• Docker Driver settings - FDO Docker - extra_hosts applied to agent containers
• Docker Compose file version 3 reference